Sleep inducing and/or comforting device for infants

ABSTRACT

A device for comforting and/or inducing sleep in an infant comprising a hollow body or other vibration transmitting means disposable at least partially beneath an infant&#39;s body or beneath or within a mattress or other body upon which an infant is laid, the space within the hollow body when provided, containing only a liquid and having at least one moveable or flexible wall portion or region permitting the body to change in volume in response to a change in the pressure of the liquid within the hollow body, the hollow body being in liquid communication or the transmitting means being in mechanical connection with a signal generator by means of an elongate tube or rod respectively whereby the signal generator can be placed at location remote from the hollow body or transmitting means, the signal generator, in use, producing pressure pulses in the liquid contained within the hollow body or vibrational movement of a predetermined pattern of varied frequency and magnitude, the pressure pulses causing vibrational movement of the moveable or flexible wall portion or region of the hollow body or the transmitting means, wherein the signal generator comprises a closed chamber or mechanical connection and an electrically powered voice coil or solenoid operatively connected to a flexible or moveable region of the closed chamber, the closed chamber being in fluid communication with the hollow body by means of the elongate tube or the means otherwise, the voice coil or solenoid being operatively connected to a programmable electronic controller whereby the flexible or moveable region of the closed chamber or the means can be reciprocated at a predetermined pattern or varied frequency and magnitude.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part under 35 U.S.C. §120 of International Application No. PCT/GB2005/001782, filed on May 9, 2005, which claims priority from Great Britain Application No. 0410537.5, filed on May 11, 2004.

The present invention relates to a device for inducing sleep and/or comforting infants and more particularly a device for inducing sleep and/or comforting infants by inducing a vibrational motion to the infant simulating the motion an infant experiences when travelling in a moving buggy. Parents know, through experience, that such movements can help calm restless babies. Typical buggy movements have been recorded and measured, and have been found to cover a frequency spectrum ranging from sub 1 Hz to approximately 30 Hz, with peaks at about 1-4 Hz (a walking rhythm), and at 12-18 Hz (activity and motion), with lower amplitude, random gentle vibrations filling out the remainder of the spectrum as ‘brown noise’.

Whilst prior art devices, such as that disclosed in GB 2,359,994, are known comprising an air inflatable bladder which can be placed beneath an infant and connected to a reciprocating pump for generating cyclic pulses to simulate the rhythm of a mother's heartbeat as experienced by a baby in the womb, such prior art devices are not suitable for reproducing the frequency range or magnitude of the complex vibrations experienced by an infant when travelling in a buggy. The prior art devices cannot produce the vibrations experienced by an infant travelling in a moving vehicle, which are also known to induce sleep in infants. Parents can use the present invention to simulate all these types of vibrations.

U.S. Pat. No. 4,066,072 discloses a mattress for infants which supports the whole child and has a rotary fluid pump which pumps fluid into the mattress via an inlet conduit and the fluid is returned via a separate conduit. WO 0213753 discloses a pulsating device which circulates water via multiple water transfer tubes in a foam-filled bed or mattress to prevent buckling and impede water flow.

Alternative devices such as bassinets and baby chairs with built-in vibration inducing means are commercially available and marketed as having a calming and sleep inducing effect; generally the said vibration inducing means are battery powered, motor driven, eccentrically rotating bob weights, providing one or more constant speeds of rotation and frequencies of vibration. The vibrations these devices induce are repetitive, insistent and restricted to the set frequency; they do not simulate well the type of motion a baby will experience when being carried in a buggy, a moving vehicle, or by a walking person. The movements the present invention seeks to induce are gentler, more variable and made up of a complex spectrum of frequencies.

According to the present invention there is provided a device for comforting and/or inducing sleep in an infant comprising a hollow body disposable at least partially beneath an infant's body or beneath a mattress or other body upon which an infant is laid, said hollow body containing a liquid and having at least one moveable or flexible wall portion or region permitting the body to change in volume in response to a change in the pressure of the liquid within the hollow body, said hollow body being in liquid communication with a signal generator by means of an elongate tube whereby the signal generator can be placed at a location remote from the hollow body, said signal generator, in use, producing pressure pulses in the liquid contained within said hollow body of a predetermined pattern of varied frequency and magnitude, said pressure pulses causing vibrational movement of the moveable or flexible wall portion or region of the hollow body of a frequency and magnitude such as preferably simulating the motion experienced by an infant when travelling in or being carried by a buggy or other moving vehicle. Preferably at least a portion of the elongate tube is flexible. The device of the invention defines a closed liquid system which transmits the movements created by the signal generator to the hollow body disposed under the infant by means of pressure pulses and small oscillations in the liquid. The liquid carrying cavities of the device are as small as is compatible with transmitting these movements efficiently and accurately; these cavities are not filled with foam nor any other material (other than liquid) that may adversely affect the transmission of the signals in contrast to one of the prior art disclosures.

Preferably a single elongate tube is provided although it is considered possible to have multiple tubes leading to multiple bags/hollow bodies (even smaller ones), or more than one tube leading to one bag, so long as the water does not circulate.

In a preferred embodiment the signal generator comprises a closed chamber and an electrically powered voice coil or solenoid operatively connected to a flexible or moveable region of said closed chamber, said closed chamber being in fluid communication with said hollow body by means of said elongate tube, said voice coil or solenoid being operatively connected to a programmable electronic controller whereby said flexible or moveable region of said closed chamber can be reciprocated at predetermined patterns or varied frequency and magnitude. Preferably the signal generator is capable of producing vibration of the moveable or flexible region of the hollow body at a frequency of between 1 and 40 Hz (1-40 cycles per second) contoured noise. Note that the complex vibrations needed are created from the combination of a contoured spectrum of frequencies (a number of different frequencies of between 1 and 40 Hz overlaid one on top of another), not just from one frequency. This is what is known as ‘noise’, and is the type of vibrations the infant encounters in a buggy or being carried. A number of excitation patterns might be provided. Preferably the signal generator and all electrical components and components emitting electromagnetic radiation are placed outside the infant's cot or bassinet, some distance from the infant.

Preferably the liquid contained within the hollow body comprises an inert, safe, relatively incompressible liquid. In a preferred embodiment the liquid is water or more viscous liquid/gel combination that is still capable of transmitting the vibrations. The total volume of the liquid contained with the device may be less than 200 cm³, possibly about 100 cm³ but preferably greater.

In one embodiment, the hollow body, to be filled only with liquid, may comprise a flexible bladder. Alternatively the hollow body may comprise a first rigid portion, and said at least one moveable or flexible wall portion or region comprises a rigid wall section joined to said first rigid portion of the hollow body by means of a flexible diaphragm whereby said first rigid portion of the hollow body and the diaphragm together define a closed chamber. The diaphragm may be clamped to said first rigid portion of the hollow body by a substantially circular plate like member with a corresponding opening within which the diaphragm sits, holding and sealing the periphery of the diaphragm against the first rigid portion of the hollow body. The said moveable rigid wall section attached to the diaphragm, when positioned under a mattress, will spread the movement of the diaphragm over a larger area of the mattress.

In an alternative embodiment of the invention the liquid transmission means is replaced by a mechanical one such that a device for comforting and/or inducing sleep in an infant comprises a movement or vibration transmitting member, disposable at least partially beneath an infant's body or beneath or within a mattress or other support means upon which an infant is laid, the transmitting member or device having at least one vibratable portion or region permitting the member or device to transmit vibrations communicated from a signal generator by means of an elongate mechanical vibration communicating means whereby the signal generator can be placed at location remote from the vibration transmitting device, said signal generator, in use, producing vibrations in the transmitting member of a predetermined pattern of varied frequency and magnitude, wherein the signal generator comprises an electrically powered voice coil or solenoid with the moving part thereof being operatively connected to one end of said elongate mechanical vibration communicating means, said voice coil or solenoid being operatively connected to a programmable electronic controller whereby said vibration transmitting member can be reciprocated at a predetermined pattern or varied frequency and magnitude.

The vibration transmitting means includes biasing means such as a spring or other resilient means providing a restorative force against the displacements in a direction caused by the vibrator communication means to provide effective vibration transmission. The inventive steps on the mechanical system include a) using a voice coil and b) also by using springs to tension each end of the Bowden cable so that it can transmit both push and pull forces (without springs it could not easily push, especially for example, as the inner core of a Bowden cable is flexible).

The present invention will be described further, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a plan view of a device according to a first embodiment of the invention, including schematic illustration of the solenoid and electronics;

FIG. 2 is a perspective view of a device similar to that of FIG. 1 but wherein the tube is bent and leads to the signal generator which is in a housing containing the electronics, solenoid and driving chamber and other controls;

FIG. 3 is a vertical sectional view of the device of FIG. 1 taken along line A-A;

FIG. 4 is a perspective sectional view of a first part of the device of FIG. 1 sectioned along line A-A;

FIG. 5 is a perspective sectional view of a second part of the device of FIG. 1 sectioned along line A-A;

FIG. 6 is a perspective view similar to FIG. 4 of a slightly modified hollow body;

FIG. 7 is an exploded view of the hollow body of FIG. 5;

FIG. 8 is a perspective view from above of an infant comforting device forming a second embodiment of the invention;

FIG. 9 is a plan view of the device of FIG. 8;

FIG. 10 is an end elevation of the device of FIG. 9;

FIG. 11 is a schematic side elevational section of a device with a mechanical connection between a voice coil/solenoid and a movement transmission member forming a third embodiment of the invention;

FIG. 12 is a section on the line A-A of FIG. 11;

FIG. 13 is an enlarged detail at B of FIG. 12; and

FIG. 14 is an enlarged detail of the voice coil and cable connection part of FIG. 12;

FIG. 15 is a schematic perspective view of the device of FIG. 12, for example;

FIG. 16 is an enlarged exploded view of portion E of FIG. 15;

FIG. 17 is an enlarged exploded perspective view of portion D of FIG. 15;

FIG. 18 is a perspective view of the other side of the rocking platen;

FIG. 19 is a schematic side elevation of a third embodiment of the invention wherein a voice coil depends from a resiliently mounted vibration transmission platen device by means of a connecting rod which links the voice coil vibration generator with the platen;

FIG. 20 is a plan from above of the apparatus of FIG. 19;

FIG. 21 is an enlarged section on the line A-A of FIG. 19;

FIG. 22 is an exploded schematic perspective view generally of the device of FIGS. 19 and 21;

FIG. 23 is an enlarged detail of the region in the upper left hand part of FIG. 21 showing the rubber diaphragm between the platen and base.

As shown in FIGS. 1 to 7 of the drawings, the device forming a first embodiment of the invention comprises a hollow body 1 defining a relatively thin, flat chamber or pad having a substantially square outline encased in a fabric envelope or cover 2. The hollow body 1 includes a moveable upper wall section 3 joined to the remainder of the hollow body 1 by means of a flexible diaphragm 4 such that the volume of the chamber defined by the hollow body 1 can vary in response to a variation of the pressure of a liquid within the chamber. The diaphragm 4 is of sufficient flexibility and dimensions such that the wall section 3 can reciprocate through a sufficient distance to simulate the desired vibrations. As cots and bassinets are of different sizes, and as it is intended that this device has universal application, the first part of this device does not cover the whole mattress area of a cot or bassinet. This first part of the device is likely to be placed under the cot mattress, creating vibrations through the mattress. The first part of the device should be thin and not affect the general comfort of the infant.

The hollow body 1 is connected to a first end of a single flexible, elongate tube 5 such that the interior of the tube 5 is in liquid communication with the chamber defined by the hollow body 1. This elongate tube 5, which will be laid under a mattress, must be sufficiently small in diameter not to discomfort an infant. It should also carry liquid pressure pulses efficiently so that the signal generator uses as little power as possible, as it will be driven by a low voltage transformer. As little as possible liquid in the pulsations should pass down the tube; this can be achieved by minimising the swept volume of the diaphragm of the first part of the device.

The second end of the elongate tube 5 is connected to a signal generator unit 6 (this is just the body of the device—the signal generator is not shown in detail in the drawings) comprising a driving chamber 7 in fluid communication with the interior of the tube 5, and thus the chamber defined by the hollow body 1, said driving chamber 7 having a moveable wall 8 joined to the body of the driving chamber 7 by means of a flexible diaphragm 9. The moveable wall 8 of the driving chamber forms part of or is connected to the armature 10A of a voice coil or solenoid 10 including electronic control box 10B by means of which the moveable wall 8 can be driven in response to an electrical signal supplied to the voice coil from an electronic control unit (not shown).

In the modification of FIG. 2, which is a perspective view illustrating casing/chamber 10B for the signal generator enclosing the electronics, solenoid and driving chamber, a control 10C is provided to alter the vibration pattern (may also include a timer to switch it off), and the tube is bent so that the signal generator enclosure can rest on the floor outside the infant's cot.

The closed volume defined by the driving chamber 7, flexible elongate tube 5 and the chamber defined by the hollow body 1 is filled with a relatively incompressible liquid such as water such that movement of the moveable wall 8 of the driving chamber 7 causes a variation in pressure in the liquid leading to a corresponding movement of the moveable wall section 3 of the hollow body 1. Thus it will be appreciated the system is a closed or sealed liquid system, without valves, and also is a non-circulatory system i.e. the liquid is not pumped through the hollow body via separate inlet and outlets. Also, the vibrations will not be simple sinusoidal ones.

Preferably the liquid comprises water such that any leaks pose no health risk to the infant. The total volume of the closed volume defined by the driving chamber 7, flexible elongate tube 5 and the chamber defined by the hollow body is approximately 100 cm³. Accordingly, even a total failure of the device leading to the loss of all water from said closed volume will only result in a minimal spillage. Using a small volume of incompressible liquid will make the transmission of vibrations from the signal generator to the first part of the device efficient. The size of the pad or hollow body will be approximately 160 mm square and as thin as possible (at present about 12 mm). Extendable arms (much the same shape as a ruler) or some other foldable thin structure that swing or slide out (two, three or four of them) may be attached to the top member of the hollow body, to spread the vibrations more widely under a mattress (foldable/removable for shipping).

In use, the hollow body 1 is placed beneath a mattress or other body upon which an infant is to be laid and the signal generator unit 6 is placed at a convenient location remote from said mattress by virtue of the elongate flexible tube 5. It is to be appreciated that the thin flat chamber comprising the hollow body is considerably smaller than the size of a mattress as it is intended to be used in conjunction with such, e.g. within a pocket therein, or under such to adapt such, or with another body such as a foldable fleece, or is considerably smaller than the cradle, cot/bassinet it is to be used in.

The electronic control unit is programmed with a recording of the movements and vibrations experienced by an infant when travelling in a buggy or other vehicle. The electronic control unit, which can be powered by batteries or a mains transformer, can be operated to output an electronic signal to the voice coil to generate a vibrational movement of the moveable wall 8 of the driving chamber 7. Such vibrational movement is transmitted to the moveable wall section 3 of the hollow body 1 via the liquid contained within the closed volume defined by the driving chamber 7, flexible elongate tube 5 and the chamber defined by the hollow body 1 such that the movement of the moveable wall section 3 of the hollow body 1 induces a vibrational movement to an infant resting on the mattress under which the hollow body 1 is placed, said vibrational movement having a magnitude and frequency simulating that experienced by an infant when travelling in a buggy, thus comforting the infant and/or inducing sleep in the infant.

The device can be placed beneath the normal mattress of the cot in which the baby is laid, requiring no modification of the mattress. However, it is envisaged that the hollow body 1 of the device could be placed within a pocket or recess in the mattress or be placed directly beneath the infant's body, if desired.

In FIGS. 6 and 7, a slightly modified hollow body 1A is illustrated and comprises a rectangular or square outlined base plate 11 having a central annular raised portion 12 defining a central liquid retaining region 13 into which a tubular part 14 opens at one end and, at its other end, communicates with the first end of the single flexible elongate tube 5 (not shown in FIGS. 6, 7). A flexible diaphragm 15 formed of elastomer material seats in a shoulder of portion 12 and defines the upper wall of the liquid retaining region 13. A tubular part 16 extends from the edge of base plate 11 through the portion 12 to enable filling of the device/system after which it is closed and sealed.

The diaphragm 15 is sealingly clamped in position on its seat on plate 11 by means of an annular diaphragm retainer 17 and held in position by known means (not shown). The diaphragm 15 has a central annular upstanding wall portion 15A which securely fits into a central aperture 18A in a recessed portion 18B of a top plate or moveable body 18, which is likely to be relatively stiff, which can be moved up and down (by flexing and/or other displacement) under the influence of the movement of the diaphragm 15 itself displaceable by pressure pulses in the water caused by the signal generator.

Components 11, 15, 17 and 18 are all contained within an outer fabric envelope or bag 19 of similar outline illustrated as a perspective view from above and having an opening in the left-hand side 19A. It is believed a clearer understanding will result of the construction of the hollow body 1 of FIG. 4 which is similar and shows the hollow body within its outer fabric bag.

Whilst the hollow body of the device according to the preferred embodiment is disclosed as comprising a rigid body having a moveable wall portion joined thereto by means of a flexible diaphragm, it is envisaged that the hollow body might comprise a one piece flexible bladder or similar hollow flexible body.

To illustrate such an alternative, FIG. 8 is a perspective view from above of a second embodiment of the invention wherein a voice coil or solenoid with moving part and actuator 20 has a moving part which acts on a fluid, in a similar manner to FIGS. 1 to 7, and which is contained within chambers and conduits including pipe 21 in fluid communication via inlet 22 with a rectangular flexible hollow body 23 which has a plurality of interconnected liquid receiving compartments 24 filled with liquid, such as water or water/gel, and which body 23 is to act as a mattress or an over mattress, positioned over and covering a mattress (not shown) on which an infant is to lie. The hollow body 23 is produced by welding or otherwise bonding together two layers/sheets of flexible material along a matrix of plastics interrupted weld lines to form seams 25 with flow spaces to form the interconnected liquid containing chambers and a single inlet passage 22. The liquid containing chambers 24 contain only liquid. The voice coil and actuator has the characteristics as described elsewhere herein.

The hollow body may form a mattress itself or an over mattress.

A third embodiment of the invention is illustrated in FIGS. 11 to 18 and involves a mechanical link means in the form of a Bowden cable 29 to connect the moving part 26 of a voice coil 27 or solenoid to a movement or vibration transmission member or platen 28.

Whilst as a broad concept the mechanical link means may be a concentric (rigid or flexible) rod and tube with the rod attached to the moving part of the voice coil and to the platen or other movement transmission means or vibrator unit in contact with the mattress. The outer tube is attached to the stationary part of the voice coil and to the base plate of the vibrator unit under the mattress in the cot. This works most simply if the rod and tube are rigid, so that they can both push and pull without flexing to generate movement in the actuator. If forces and movement are to be transmitted from the voice coil to the platen, and it is not done with inertia, one side of the voice coil must be connected mechanically to one side of the platen (top, for example) and the other side of the voice coil to the other side of the platen (base, for example). One of these connecting mechanical links (e.g. the outer sheath of the cable) will be in compression when the inner core is in tension (i.e. one pushing, the other pulling). In that way a force is transmitted which moves the top of the platen in relation to the bottom (it creates a force between the two parts of the platen). As we are transmitting vibrations, the forces reciprocate, so the two connecting links are cycling between tension and compression and are 180° out of phase with each other (one in tension while the other in compression and vice versa). The springs allow one of these mechanical links to be a wire (a wire cannot transmit a compression along its length—it will buckle). The rod may either have to come out horizontally, with the voice coil outside the cot at mattress level, or vertically downwards or upwards and if upwards the rod and tube may be positioned on the edge of the mattress beside the wall of a cot. If downwards, the cot floor may be slatted or at least have regular holes in it at least 10 mm in diameter, so that the rod and tube can pass through the floor of the cot to connect a voice coil below the floor of the cot to a platen above it. The rod and tube do not need to be concentric; they could be parallel to each other, but concentricity will mean that the outer sheath is stationary, which is advantageous.

As illustrated in FIGS. 11 to 18, the vibration communication means comprises a concentric rod and tube which are flexible—in other words a Bowden cable 29, such as used for example for bicycle brakes, and is connected to a vibration transmission means 35 whose main parts are platen 28 and base 37. The inner ‘rod’ is a wire 30 and the outer tube 31 a coiled flexible sheath 3. It is important to ensure the devices runs quietly and as efficiently as possible. To enable this the inner wire 30 is tensioned with a spring 32 at the voice coil 33 end where it is connected to moving part 26 and the spring 34 at the platen 28 end (which instead could be rubber or other resilient means). Thus this link is to be used with a voice coil instead of the earlier described hydraulic system and is potentially more efficient at the appropriate frequencies. The Bowden cable 29 at the platen end has its outer sheath abutting a stop 37A and the inner wire 30 is held in a lug or rocker arm 36 which is displaceable by the vibrations transmitted from the voice coil 33. The platen 28 is resiliently mounted via spring 34 on base 37 and spring 34 acts to restore or return platen 28 to its position prior to displacements by the cable 29 under the action of voice coil 33 and to tension cable 29. FIGS. 12 to 18 illustrate the same construction of vibration transmission means or rocking device.

In FIGS. 15 to 18 greater details of the coil 33 and the vibration transmission means 35 are illustrated. The vibration transmission means comprises the two cantilever arms forming base 37 and platen 28 or as shown comprising tapered platen 28 having pivot parts 38 either side of a rocker arm 36 for attachment at one end of the wire 36 of a Bowden cable (which may be flexible or rigid but as shown is flexible as mentioned). The normally underside of platen 28 has a recess 39 forming a seat for a spring 34 which seat in a similar recess 37B in a base member 37 which latter member is generally pointed or tapered and the platen 28 and base member 37 each have a recess to accommodate such. Base 37 has co-operating pivot connections 40 which co-operate with pivot parts 38 to provide a pivotal axis for the platen 28 which is to be located generally below a mattress (not shown). A tubular collar 37A is provided on the base 37 and acts as a stop for the outer sleeve 30 of the Bowden cable 29. The wire 31 is secured to rocker arm 36 and causes vibrations to be transmitted to the platen 28—the return spring 34 acting between the platen 28 and base 37 to enable such.

A further embodiment of the invention is illustrated in FIGS. 19 to 24 wherein what might be termed an ‘inertial’ arrangement is illustrated. The device 40 comprises a voice coil or solenoid 41 housed in a two-part casing comprising a lower case 42 and an upper case part 43. The voice coil 41 is provided in the casing and has a moving part 47 and the central section of the voice coil moves relative to the outer-the outer annulus of the voice coil is heavy and the centre section is attached to the lower case 42. The voice coil has three active elements—the inner coil, the outer annular magnet and the spring/motion control feature ensuring the inner and outer move concentrically and revert when no signal is applied to a neutral position referred to as the “voice coil spring” and it is to be noted the corrugated diaphragm is the device that performs this function. The outer annulus of the voice coil, which may be additionally weighted, is accelerated up and down by the electrical signal, and the reaction forces from the central section of the voice coil are transmitted through the lower case to the upper case, the connecting rod and thence to the upper platen which itself is mounted on four rubber diaphragm springs 44′.

The voice coil 41 is two parts—the inner section of the voice coil is mounted to the lower case; the outer section of the voice coil can move freely (though it will have to be held with a spring in a neutral point relative to the inner part). The outer section of the voice coil is heavy; accelerating it up and down (by passing a signal through the voice coil) generates reactive forces in the inner part of the voice coil, which are transmitted through the case and rod to the platen mounted on the rubber diaphragm springs. The extra step on the inertial system is using a voice coil to generate the vibrations.

A connecting rod 45 is secured to the top of the upper casing 43 and the casing 42, 43 and coil 41 are thus suspended therefrom The upper end of the rod 45 is secured to a vibration transmitting device 46 which will be supportable on a surface of a cot or mattress. To enable this, the device will have to be separable and the rod 45 inserted in an aperture or passage in the cot or like prior to reconnection.

The device 46 comprises a lower platen 47 having a through passage for the end of rod 45 to pass and be connected to an upper platen 48 and be connected in the centre. The platen 48 is resiliently mounted on platen 47 by four rubber diaphragm springs 44, somewhat similar in appearance to four rubber grommets, but which engage with each platen 47, 48 and space such apart and enable vibration of platen 48 when such receives vibrations from the voice coil 41 via rod 45.

Thus the voice coil is contained in a casing below the cot floor suspended by a single rod from a platen above the cot floor and the central moving coil of the voice coil is attached to the casing and the heavy outer annulus of the voice coil suspended in a neutral position relative to the central moving coil by a spring and free to move up and down relative to the central moving coil under the influence of the forces created by the electrical signal applied to the voice coil and the spring. Springs or resilient means 44 are again used in the under mattress vibrator unit 46 to allow movement between the platen and the base plate of the vibrator unit, and a spring (shown as the corrugated section of the voice coil) in the voice coil 41 to centre the two sides of the voice coil in a neutral position. This unit will only be able to be placed under the cot and, as with the rigid concentric-drive will need holes/slots in the cot floor to pass the rod through.

Thus one side of the voice coil is below the cot floor suspended on a single rigid rod, connecting a mass (a heavy(ish) weight to the other side of the voice coil. Springs or resilient means 57 are again used in the under mattress vibrator unit 54 to allow movement between the platen and the base plate of the vibrator unit, and in the voice coil 49 to centre the two sides of the voice coil when under the influence of the mass (weight). This unit will only be able to be placed under the cot and, as with the rigid concentric drive will need holes/slots in the cot floor to pass the rod through. (It is important to note that there is intended to describe embodiments of the fluid arrangement where the vibration transmitting means or the actuator is large enough to be placed in the cot (under the mattress in the same designs) or it either being a mattress topper (water or gel filled) that sits on the mattress or has the entire mattress itself and creating vibrations in the topper or mattress with a voice coil attached to a chamber located outside the cot connected via a tube to the topper in a similar manner to the existing invention. Alternatively a mechanical rather than fluid connection from the voice coil to the actuator is envisaged.

The signal generator drives a small diaphragm and in the liquid link embodiment efficiency is increased by using a single small bore tube or pipe.

The device generally may be operated remotely, preferably by means of a wireless controller to enable a parent to operate the device from a distance. The electronic control unit may include timer means to enable the device to be operated for a pre-determined time interval, automatically switching off after a pre-determined duration or at a predetermined time. Alternatively, or additionally, the device may be activated in response to the sound or movement of the baby and may operate for a pre-determined period thereafter.

Whilst the device according to the present invention is described for use in a cot or bassinet, it may be used in many other situations where a calming vibration is required.

Preferably the device does not create just one pattern of vibrations but rather different ones can be selected and preferably the vibrations are complex, created from a number of different frequencies of different magnitudes that are overlaid/combined to create the required vibrations (which is why a voice coil is a particularly suitable means for doing this). Further, the moving wall of the hollow body follows the pulses in the liquid accurately and the ‘vibrational movement’ of the moving wall of the hollow body more clearly to the patterns of excitation created by the signal generator. 

1. A device for comforting and/or inducing sleep in an infant comprising a hollow body disposable at least partially beneath an infant's body or beneath or within a mattress or other body upon which an infant is laid, the space within said hollow body containing only a liquid and having at least one moveable or flexible wall portion or region permitting the body to change in volume in response to a change in the pressure of the liquid within the hollow body, said hollow body being in liquid communication with a signal generator by means of an elongate tube whereby the signal generator can be placed at location remote from the hollow body, said signal generator, in use, producing pressure pulses in the liquid contained within said hollow body of a predetermined pattern of varied frequency and magnitude, said pressure pulses causing vibrational movement of the moveable or flexible wall portion or region of the hollow body, wherein the signal generator comprises a closed chamber and an electrically powered voice coil or solenoid operatively connected to a flexible or moveable region of said closed chamber, said closed chamber being in fluid communication with said hollow body by means of said elongate tube, said voice coil or solenoid being operatively connected to a programmable electronic controller whereby said flexible or moveable region of said closed chamber can be reciprocated at a predetermined pattern or varied frequency and magnitude.
 2. The device as claimed in claim 1, wherein a single elongate tube is provided.
 3. The device as claimed in claim 1, wherein the signal generator is capable of producing vibration of the moveable or flexible region of the hollow body at a frequency of between 1 and 40 Hz.
 4. The device as claimed in claim 1, wherein the liquid contained within the hollow body comprises water.
 5. The device as claimed in claim 1, wherein the flexible or moveable wall portion of the hollow body includes a flexible diaphragm forming a wall of the liquid containing part of the hollow body connected in displacing relationship to an upper moveable plate member for transmitting the vibrations to an infant or to the mattress on which an infant is placed or to be placed.
 6. The device as claimed in claim 1, wherein the total volume of the fluid contained with the device is less than 200 cm³, possibly about 100 cm³ or preferably greater.
 7. The device as claimed in claim 1, wherein at least a portion of said elongate tube is flexible.
 8. The device as claimed in claim 1, wherein the hollow body comprises a flexible bladder.
 9. The device as claimed in claim 1, wherein said hollow body comprises a first rigid portion, said at least one moveable or flexible wall portion or region comprising a rigid wall section joined to said first rigid portion of the hollow body by means of a flexible diaphragm whereby said first rigid portion, diaphragm and rigid wall section together define a closed chamber.
 10. The device as claimed in claim 8, wherein said rigid wall section includes a substantially circular liquid containing portion as part of a base plate member, said diaphragm being connected between the periphery of said circular portion and an opening in said first rigid portion.
 11. The device as claimed in claim 1, in which the signal generator is such as to cause vibrational movement of a frequency and magnitude simulating the motion experienced by an infant when travelling in a buggy or other vehicle.
 12. The device as claimed in claim 8, in which the flexible bladder forms a mattress or over mattress and comprises a flexible body partially divided into a plurality of interconnected compartments filled with liquid.
 13. A device for comforting and/or inducing sleep in an infant comprising a movement or vibration transmitting member, disposable at least partially beneath an infant's body or beneath or within a mattress or other support means upon which an infant is laid, the transmitting member or device having at least one vibratable portion or region permitting the member or device to transmit vibrations communicated from a signal generator by means of an elongate mechanical vibration communicating means whereby the signal generator can be placed at location remote from the vibration transmitting device, said signal generator, in use, producing vibrations in the transmitting member of a predetermined pattern of varied frequency and magnitude, wherein the signal generator comprises an electrically powered voice coil or solenoid with the moving part thereof being operatively connected to one end of said elongate mechanical vibration communicating means, said voice coil or solenoid being operatively connected to a programmable electronic controller whereby said vibration transmitting member can be reciprocated at a predetermined pattern or varied frequency and magnitude.
 14. The device as claimed in claim 13, in which the vibration communicating means is inertial (either done with a single rod and a weighted voice coil) or by mechanical push or pull means (such as with a Bowden cable, rigid or flexible or concentric rod type).
 15. The device as claimed in claim 14, whenever in contact with a cot or bed having a slatted/perforated suspended floor wherein the rod is passed therethrough, and the vibration transmitting device is located under a mattress.
 16. A device for comforting and/or inducting sleep in an infant comprising a vibration transmitting member disposable at least partially beneath an infant's body or beneath or within a mattress or other body upon which an infant is laid, the transmitting member having at least one vibratable part, portion or region permitting the member to transmit vibrations communicating from a signal generator by means of an elongate mechanical vibration communicating means whereby the signal generator can be placed at location remote from the hollow body, said signal generator, in use, producing vibrations in the transmitting member of a predetermined pattern of varied frequency and magnitude, wherein the signal generator comprises an electrically powered, weighted voice coil or solenoid suspended by a rod connected to the non-weighted side of the voice coil such that the reactive forces created in accelerating the weighted side of the voice coil up and down are transmitted through the rigid rod to the vibration transmitting means/platen to create inertial vibrations, said voice coil or solenoid being operatively connected to a programmable electronic controller whereby said flexible or moveable region of said vibration transmitting member can be reciprocated at a predetermined pattern or varied frequency and magnitude. 